SiO2/6H-SiC(0001)3x3 initial interface formation by Si overlayer oxidation

We investigate the initial oxidation and SiO2/6H-SiC interface formation by core level photoemission spectroscopy using synchrotron radiation. The results indicate that the direct oxidation of the 6H-SiC(0001)3x3 surface leads to SiO2 formation at low temperatures (500 degrees C) with a nonabrupt interface having significant amounts of mixed (Si-O-C) and intermediate (Si3+,Si2+,Si+) oxidation products. In contrast, C-free and a much more abrupt SiO2/6H-SiC(0001) interface formation is achieved when predeposited Si overlayer is thermally oxidized at low oxygen exposures and low temperatures (500 degrees C). (C) 1999 American Institute of Physics. [S0003-6951(99)04645-8].